1. Field of Invention:
This invention relates to an apparatus and method for generating electrical power, and more particularly, an apparatus and method for converting the energy contained in large ocean streams into usable electric power.
2. Description of the Prior Art:
Conventional power sources such as natural gas and oil are being rapidly depleted throughout the world. Alternative sources such as natural fluid streams or currents are presently under investigation since such sources are readily available and inexhaustible.
Accordingly, the prior art is replete with devices and methods for converting the energy contained in natural fluid streams, such as the wind and the tides, into usable electric power. Windmills commonly found on land is just one example of such an attempt to turn energy in a natural fluid stream into electric power, while turbines driven by the flow of trapped tidal waters are another. Prior attempts to convert such energy have usually failed for a number of reasons. The cost of the apparatus to convert the energy stored in a natural flowing stream has usually been prohibitive. Further, tidal and wind motion is unpredictible in nature and apparatus must be provided to store energy during peak periods of wave and wind activity for later use. The power generated from such devices is also unpredictible since electrical output fluctuates in accordance with fluctuation in wind and wave activity.
The apparatus and method of the present invention is based on an entirely different approach. An economical apparatus has been designed for installation in large ocean streams or currents, such as the Gulf Stream, to generate electrical power in large quantities. Ocean currents, as distinguished from wind and tide activity, are of a steady and predictible nature, and are in concentrated regions in close proximity to land, wherein the power can be taken directly to land by electrical cable. The velocity of such ocean streams and temperature gradings are well known and vary within precise limits, so that an apparatus can be designed with a steady and predictible output. No electrical storage facilities are needed because such current velocities are essentially constant, which results in reduced cost and increased efficiency of the equipment used for such purposes. Because the mass flow rate of water is the same for the upper and lower portions of the currents and the currents flow in a fixed direction and magnitude, there is no need for additional static support structure, but an apparatus can be designed based on hydrodynamic buoyant and lift forces.
The use of ocean currents, as distinguished from wind and tidal currents, for the generation of electrical power has been attempted. However, such attempts have operated on an entirely different principle than direct conversion of mechanical energy to electric power. For example, the difference in the ocean thermal gradients of the current have been used to generate water vapor or the vapor of some intermediate working fluid such as Freon. This vapor is then expanded through turbines to drive generators, synchronized to an A.C. net. The A.C. electrical power is then transported along tether lines to anchor points in the sea bed, collected in larger sea bed cables, carried ashore, and transported as high voltage A.C. power.
The only attempt known for obtaining electrical power directly from the current of a body of water is described in U.S. Pat. No. 868,798, issued Oct. 22, 1907. In this patent, a plurality of devices for generating electrical power are disclosed. Each device includes a propeller in the current or water flow stream, which turns in response thereto. Rotation of the propeller produces rotation of a shaft directly connected to an electrical generator. Electrical current from the generator is taken off through electrical conductors directly to a power transmission line on land. However, the current generated from each device would not be in phase with that generated from the other devices and accordingly, is not usable.